Fri, 29 Jun 2007 08:38:01 -0700 from Ariel
:
Assume that the mean and SD of the first group is 0.50 and 0.224,
respectively. We estimate that the second group will have a mean value of
0.045 (difference between the two groups is 10%). I can even throw in that we
estimate that the second group's SD will be 0.212.

What will the sample size needed to acheive this in the second group,
assuming a power of 80% and an alpha of 0.05.?

Ask in a statistics group. The formula is pretty trivial, once you
know what the calculation should be.

--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://OakRoadSystems.com/